VMware ESX Server AMD fxsave/restore Issue

Summary
A vulnerability in VMware allows attacker to exploit an AMD fxsave/restore security vulnerability which in turn can be used to disclose sensitive information.



Credit:
The information has been provided by VMware Security team.
The original article can be found at: http://kb.vmware.com/kb/2533126

Details:

Vulnerable Systems:
* ESX Server version 3.0.0 without any patches

Immune Systems:
* ESX Server version 3.0.0 with the fxsave/restore patch

The instructions fxsave and fxrstor on AMD CPUs are used to save or restore the FPU registers (FOP, FIP and FDP). On AMD Opteron processors, these instructions do not save/restore some exception related registers unless an exception is currently being serviced. This could allow a local attacker to partially monitor the execution path of FPU processes, possibly allowing them to obtain sensitive information being passed through those processes.

The Common Vulnerabilities and Exposures project (cve.mitre.org) assigned the name CVE-2006-1056 to this issue.

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Solution:
1. Log into the ESX Server service console as root.
2. Create a local depot directory.
# mkdir /var/updates
Note: VMware recommends that you use the updates directory.

3. Change your working directory to /var/updates.
# cd /var/updates

4. Download patch ESX-2533126 from http://www.vmware.com/download/vi/
into the /var/updates directory.

5. Verify the integrity of the downloaded tar file:
# md5sum ESX-2533126.tgz

6. The md5 checksum output should match the following:
f34bd684a50a29d667bd0ea5c8c8ef63 ESX-2533126.tgz

7. Extract the compressed tar archive:
# tar -xvzf ESX-2533126.tgz

8. Change to the newly created directory, /var/updates/ESX-2533126:
# cd ESX-2533126

Installation Instructions:
Once you have downloaded and extracted the archive, and if you are in the directory you created above, install the update using the following command:
# esxupdate update

For more information on using esxupdate, please refer to the Patch Management for ESX Server 3 tech note at http://www.vmware.com/pdf/esx3_esxupdate.pdf.

Note: This security patch is part of the October 2006 patch release for VI3. A second (non-security) patch is also available. Installation of these two patches is independent and you do not need to install both to be in a supported state. The other patch is available at http://kb.vmware.com/kb/2666943